A tool for a bag forming machine for deforming a web of wrapping material including one layer into a tube is known from Swiss Patent No. CH 490 995. The tool includes a forming shoulder including a plurality of parts and a filling pipe. The forming shoulder is designed to be divided in a division plane, the division plane being defined by the center axis of the filling pipe and of the forming shoulder and by the center line of the wrapping material. The forming shoulder is also divided in a second division plane, the second division plane being located vertical and parallel to the axis of the roll from which the wrapping material is wound off. The forming shoulder thus includes a stationary part and two movable parts. The movable parts of the forming shoulder are arranged to be manually pivotable with respect to one another about two rotational axes extending parallel to the center axis. In this way, they may attain a closed position and an opened position. The rotational axes of the movable parts of the forming shoulder are located in a second division plane through the center axis. The two pivotable parts of the forming shoulder are movable into the closed position and into the opened position to simplify introduction of the wrapping material into a channel between the forming shoulder and the filling pipe. The forming shoulder includes a guiding surface for the wrapping material and the channel for arranging the filling pipe. In the opened position of the two pivotable parts of the forming shoulder, the filling pipe may be pivoted about a horizontal axis and a vertical axis out off the channel. A passage gap continuously extending over the circumference is located between the filling pipe and the channel. The passage gap serves for passage of the wrapping material and of the tube, respectively. It is not disclosed in this prior art reference if and how the tube can be sealed by a longitudinal seal. When pivoting the pivotable parts of the forming shoulder into the opened position and when pivoting away the filling pipe, the interior of the forming shoulder becomes accessible for simplified handling of the wrapping material to be introduced. However, substantial skills are required to attain a stable starting position of the wrapping material to begin production. When pivoting the pivotable parts of the forming shoulder into the opened position, the pivotable parts are pivoted by 180° in an outward direction such that it is necessary to arrange a plurality of webs of wrapping material comparatively far away from one another. When pivoting the pivotable parts of the forming shoulder into the closed position, gaps being formed at the forming shoulder in a longitudinal direction are closed in the region of the joints such that there is the danger of squeezing the wrapping material.
A vertical bag forming machine including a tool including a forming shoulder and a filling pipe is known from German Patent Application No. DE 103 30 852 A1 corresponding to US Patent Application No. US 2005/0044822 A1. The forming shoulder is designed to be divided in a vertical division plane such that the forming shoulder can be opened. The division plane is arranged parallel to the axis of the roll from which the wrapping material is unwound, and it extends through the center axis of the filling pipe. In this way, a shoulder sleeve including two separate shoulder parts is formed. Furthermore, structural units including one sleeve part and one trim part are formed. One structural unit can be removed from the other structural unit to be capable of removing the filling pipe from the forming shoulder in a transverse direction with respect to the transporting direction. Due to the change of the distance between the structural units, it is also possible to produce bags of different widths. The accessibility of the interior of the divided forming shoulder, for example for simplifying introduction of the wrapping material, is only slightly increased. There is the danger of the wrapping material being squeezed or clamped when pivoting the parts of the forming shoulder into the closed position. Adjustment of the parts of the forming shoulder with respect to one another for variation of the width of the bags is conducted manually when setting up the bag forming machine.
A divided forming shoulder for a bag forming machine is known from German Patent Application No. DE 102 51 072 A1. The division plane between the two parts of the forming shoulder extends in a vertical direction in a way that a plane parallel to the separation plane extends through the axis of the roll from which the wrapping material is unwound. The known machine includes an adjustment unit for changing and fixing the distance between the two parts of the forming shoulder. This serves to easily adapt the machine to a different width of the wrapping material. During operation of the bag forming machine, the two parts of the forming shoulder are arranged to be stationary and not to move with respect to one another. Changing the distance between the two parts of the forming shoulder is only realized when changing the setting of the bag forming machine for adaption to a wrapping material having a different width.
A tool for a bag forming machine including a forming shoulder and a filing pipe is known from German Utility Model No. DE 203 20 160 U1. The forming shoulder includes a channel for arrangement of the filling pipe. A passage gap for passage of the wrapping material being deformed into a tube is located between the filing pipe and the channel. The channel begins at a deflecting edge. The deflecting edge results from an intersection line of the guiding surface of the forming shoulder in the introduction part with the channel. The deflecting edge does not continuously extend over the circumference of the channel, but it is designed to have an opened rim. The shoulder-like collars of the forming shoulder are usually designed not to be symmetric and to overlap. When the wrapping material is pulled over the forming shoulder and enters the channel, there is friction resulting in wear and tear. Wear and tear substantially influences the deflecting edge. A pulling force by a discharging device of the bag forming machine acts upon the wrapping material. The pulling force determines the pressure of the wrapping material against the deflecting edge. The disadvantageous friction conditions and conditions of wear and tear in the region of the deflecting edge are the reason for the fact that the forming shoulder can only fulfill its desired function during a limited period of time, and it then needs to be replaced. To make replacement of the forming shoulder easier and less expensive, the forming shoulder is designed to include a plurality of parts, and it includes a small insert forming a part of the forming shoulder in the region of the deflecting edge. Consequently, it is only necessary to replace the insert instead of the entire forming shoulder. The insert may be made of a harder material than the remaining part of the forming shoulder. During operation of the bag forming machine, the two parts of the forming shoulder are fixedly interconnected, especially by screws. The insert is only detachable and attachable when the worn insert is to be replaced by a new insert.
A forming shoulder including a plurality of parts for a bag forming machine is known from German Patent Application No. DE 102 09 356 A1 corresponding to US Patent Application No. US 2003/0163979 A1. The forming shoulder serves to form a double tube such that the channel extending through the forming shoulder has a comparatively complicated surface. To simplify manufacture of the channel from a block of solid material, the forming shoulder is divided by a division plane into three parts. In this known vertical bag forming machine, the division plane extends in a vertical direction through the middle axes of the two channels forming the double tube. The two detachable parts of the forming shoulder form covers for the channel. The division plane thus extends parallel to the backward plane of the forming shoulder. If one imagines the tube-like deformed wrapping material in the region of the channel to be deformed back into its plain configuration, the division plane is located in the plane of the wrapping material. During operation of the bag forming machine, the parts of the forming shoulder are fixedly interconnected, and they thus cannot be moved with respect to one another.
A bag forming machine for deforming a plain web of wrapping material into a tube is known from German Patent No. DE 698 03 525 T2 corresponding to U.S. Pat. No. 6,052,970. The bag forming machine does not include a forming shoulder, but instead a plurality of spaced apart forming rollers. To optimize the sealed condition of the overlapping portions of the tube-like web, the height position of the lower forming roller can be adjusted in a perpendicular direction.